Inverse relationship between matrilysin expression and proliferative activity of cells in advanced gastric carcinoma

Matrilysin is known to play an important role in tumor invasion, but it is not known yet whether there is a direct relationship between matrilysin expression and cell proliferation. Therefore, we compared expression of matrilysin with expression of Ki-67, a marker of cell proliferation, at different tumor areas in 130 advanced gastric carcinomas. Both matrilysin and Ki-67 were distributed heterogeneously in tumor tissue. Matrilysin frequently was expressed at the invasive front, whereas Ki-67-positive cells frequently were located both at the tumor surface and in central tumor cell nests. The patterns of gastric cancer cell invasion into the surrounding tissues are described as alpha-infiltration, beta-infiltration, and gamma-infiltration, respectively, according to the guidelines of the Japanese Research Society for Gastric Cancer Study. The mean matrilysin labeling index (LI) of gamma-infiltration tumors at the invasive front was significantly greater than that of alpha- and beta-infiltration tumors (P =.01). In contrast to the matrilysin LI, the mean Ki-67 LI of gamma-infiltration tumors was significantly lower than that of alpha- and beta-infiltration tumors (P =.02). Moreover, Ki-67 antigen was absent in matrilysin-positive tumor cells and vice versa. We concluded that matrilysin expression was related inversely with proliferative activity of tumor cells and that matrilysin expression could possibly serve as a useful marker of tumor invasion.